


Shake Your Tailfin

by mattzerella_sticks, Psynatural



Category: Supernatural
Genre: Adventure & Romance, Alternate Universe - Mermaids & Mermen, Amulets, Boats and Ships, Confused Castiel (Supernatural), Curious Castiel (Supernatural), Father-Son Relationship, Feelings, Finding Nemo (2003) References, Fisherman Dean, Flustered Castiel (Supernatural), Gay Dean Winchester, Little Mermaid Elements, M/M, Merman Castiel, Merman Dean, Near Death Experiences, Prince Castiel (Supernatural), Shipwrecks, Soft Castiel (Supernatural), Soft Dean Winchester, Transformation, Under the Sea, When Two Worlds Collide
Language: English
Status: Completed
Published: 2019-06-18
Updated: 2019-06-09
Packaged: 2020-04-23 07:23:09
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 17,052
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/19146262
Author URL: https://archiveofourown.org/users/mattzerella_sticks/pseuds/mattzerella_sticks, https://archiveofourown.org/users/Psynatural/pseuds/Psynatural
Summary: Castiel, the youngest Prince of the Seven Seas, has the most absurd fascination with humanity. Against the wishes of his father King Charles he spies upon them whenever their strange vessels enter nearby waters. It's the most innocent of hobbies until his father discovers him. After a disastrous fight, the humans' vessel floats destroyed. Everyone aboard dead save for one human. Castiel, in a surprising show, saves him.He thought now he would have his own personal human to study, but he wasn't prepared for the human to stumble upon a forgotten merperson artifact and change both their worlds forever.





	1. When Ships Collide

**Author's Note:**

> **Artist notes from Psynatural:**  
>  I created the art and story prompt as part of the 2019 Dean/Cas Reverse Bang challenge. Working with mattzerella_sticks has been a great joy and I love the fun adventure "tail" that he wrote inspired from my art.
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> **Author notes from mattzerella_sticks:**  
>  I wrote this story after being inspired by the beautiful art Psynatural created. Our partnership was amazing from beginning to end and I'm so glad that we can finally share this "tail" we've spent a lot of time and energy on. Hope you enjoy!

 

Castiel’s most dangerous quality is his curiosity. Like a ferocious riptide his need to know everything pulls him out into uncharted waters. His siblings thinks his interests are boring, and his dad would be so mad a storm would brew without much thought. Still, the risks are worth it for Castiel to indulge in making the volcanic vent in the pit of his gut rumble to life and filling his entire being with a warm, glowing awe when viewing the wonders of humanity.

As a merperson, the rules clearly state that the world of the sea and those of the land should never meet. After the disastrous first time, King Neptune from thousands of years ago struck down his trident and made his decree law. So Castiel’s people stuck to the safety of the dark waters, knowing humans were unable to venture that far down on their own. There were some benefits to his people.

Their powerful tails are one. They made traversing the waters easy with the thick muscles and streamlined fins.

Castiel had always been singled out by the color of his. Blue was rare for a merperson. An old legend told how those born with scales the color of the sea were blessed with its protection. He never put much stock in the fairy tales of old, but sometimes when he would sit and stare at his glowing tail, run his hands down its smooth surface, he remembered some myths have a pearl of truth hidden inside.

That’s not to be said about all of them. Most were created as warnings to keep children far away from places they shouldn’t be; he should know, Castiel studied them all. The story of the deep, a crack in the ocean where horrible creatures were said to live the farther you go down. One of how you must always flee when a giant squid floats by, or you would be taken away to be its newest pet. Or the tale of the mermaid princess running afoul of a sea hag and having her birthright ripped away in a hideous transformation, from mermaid to human.

Castiel loved that one from the first time he heard it, when he was nothing more than a guppy following his older brothers around with wonder in his eyes. Lucifer would tell him all the stories while Michael rolled his eyes and kept to his studies. Looking back, his brother was trying nothing more to scare him. But all he did was lay the foundation for his interests today.

Humans were confounding creatures. They weren’t made for the ocean yet many still spend time within it. Hubris, his dad said, was what made them break from their borders and seep into theirs.

He blamed many things on humanity’s grandeur sense of itself. “They don’t respect the ocean like we do,” he told him, “They have their own land yet they take from ours as well? Machines attacking our communities, absconding with our food, laying waste to all they touch… they’re a parasite to the very balance of our ecosystem. A threat to our people’s way of life.”

Castiel tuned his father out when he got fired up like that. It was the same song and dance repeated whenever a scout came back to him about the strange, hard-shelled fish humans sent down to expose them. They didn’t know what they were at first, having never seen one before. But after breaking it apart and dissecting it for information, the royal scientists discovered the purpose of humanity’s pet. And as king, Castiel’s father issued a warning that anyone caught playing with or around it would be banished from the kingdom and branded a traitor – even his own sons.

Castiel’s curiosity is very dangerous, especially given his status and the owner of his attention. What the court would say if they knew the youngest prince of King Charles was obsessed with humanity!

But it wasn’t an obsession he’s _intrigued_. There are many things about them that both confound and astound Castiel. Like the two fins they have instead of one, and how they can use them for more than swimming. Or their strange way of speaking that delighted Castiel’s ears. He understands none of it, but knows there were so many variations to the siren song. As if each boat had its own unique way of speech. But the real reason he watched them, the anglerfish’s hypnotic glow for him, was their freedom.

In merculture, you were born into an assigned role and had no way to negotiate for anything else. If your parents were palace guards, then one day you would be one as well. And a prince stays a prince, carrying with him all the rules that come alongside it.

Humanity didn’t seem to have this problem. Each time Castiel poked his head out of the water he was greeted to the joyous caws and wondrous sights of humans smiling. Swimming out of sight, Castiel saw the humans in their large, whale-like vessels _enjoying_ their time at sea. Like the ocean wasn’t a disappointed mother who you spent your entire life trying to live up to her expectations and fulfill your duties. She was a friend, someone who only wanted to provide.

Like now, Castiel looks on as a group of humans toss nets into the ocean. It’s very clearly work but they do it all while laughing and grinning. His people were very stoic, and the thought of having fun while in the middle of a job was itself laughable. Humans made it look so simple…

“Castiel!”

He startled, ducking down back into the water. Another splash sounded soon after following him. Spinning around, Castiel comes face to face with his best friend and personal guard Hannah. She glares at him, tail tense as it sways to keep her level with him.

“Castiel,” she repeats, “What do you think you’re doing?”

Chuckling, Castiel ran fingers through his hair. “Checking out the giant vent above?”

Clearly not amused, Hannah circles him. She hisses, “Do you know how much trouble you could get into if your father were to find you here? How much trouble _I_ could get into? Swimming near humans –“

“They weren’t going to notice me,” Castiel tells her, “It’s not like I’ve done it before.”

“That doesn’t make it better!”

“You don’t get it Hannah,” he sighs, glancing towards where the water ripples and stray beams of light cut across. Castiel floats a hand through them, delighting in their warmth. “I wasn’t going to approach them, only watch. They’re quite amusing from afar… and I’m learning so much! Like this…” He holds his longest finger, the one in the middle, aloft in her direction, “it’s a common gesture shared amongst humans… I believe it means something along the lines of love, whenever it’s done a human usually shouts in excitement!”

“Put that down,” Hannah cries. She seizes his wrist, tugging it, “You are no human! You’re a merman – a _prince_ – and as such you have duties to perform. Duties that you were supposed to be at…”

Castiel freezes. “What? No, I haven’t been here that long…”

“Castiel the rehearsal for tonight’s feast is already half over,” Hannah says, “If I didn’t lie to your father – _my king_ – about where you were it might not have been me who found you.”

“It’s nice to finally hear the truth from you, Hannah.”

The water around them drops in temperature; the cold pricking into his skin as through urchins swarmed the area. Both he and Hannah turn, finding Castiel’s father swimming their way.

“Oh ink…”

“Castiel,” Charles says, towering over them. With the added height from his crown, he cuts an impressive figure. It’s clear he’s about to begin a grand lecture by the bend of his brow and tenseness of his jaw. Still, Castiel doesn’t shy away. Instead he closes the distance between them, cutting his father off before he can begin and meets his angry stare with one of his own.

“Father,” Castiel greets him, “So nice to see you outside of the castle.”

Charles does not do well with interruptions. “Impudence, really?” his father asks, “Others with more sense would be begging for forgiveness at this point in time.”

“And what exactly do I need to apologize for?”

His large hand swoops wide, trident dangerously pointing at where the boat rests in the water. “ _Humans_ are tricky beasts, my son,” Charles seethes, “I have spent countless hours instilling this into you and all your siblings –“

“You’ve been spouting the same bilge that’s been going around for thousands of years!” Castiel shouts, “Do you have any idea that what you say is the truth?”

“It’s what I _know_.”

“Well maybe you don’t know everything!” Castiel finally says, “You’ve never met a human – _talked_ with a human! You’re just espousing the same tales parents tell their kids.”

“I don’t have to study them to know what they are,” Charles tells him, “A plague, something you should avoid before you find yourself _infected_ with their stink.”

“They’re beings, not much different than us –“     

“You hold your tongue, Castiel,” Charles hisses, “Flapping it around any further like a finless fish will prove more harm than good.”

Castiel stutters in response, growling as he encounters his father’s well-entrenched walls. His fists slam and disturb the water around him the further the tides of his anger ebb and flow. “I’m surprised I have the strength for my tongue to ‘flap around’,” Castiel says, “That I have not bitten it off yet a testament to my patience.”

“It’s the duty of a politician to know when and what to speak,” Charles says, “And today proves that you might only be prince in name but not in spirit…” He turns around, continuing to himself. “I’ve been to lax… pushed too much off on your elder siblings, believing you were not ready. Maybe it’s best you learn under pressure.”

Castiel did not care being brushed aside like that. His father ended his arguments poorly; many a time Castiel was left floating in a hallway after getting into it with his father. Charles swimming away with the final word like he won. He would not this time.

“I never asked to be a prince in name or spirit,” he yells, catching Charles’s attention, “I’m surprised that spirit is such a necessity in a job that demands you tear out your heart.”

Charles slowly returns to him, glaring. The water around them gets choppier, pulled in different directions by the glow of his father’s trident. Castiel stays, not letting himself be pushed around.

“You know nothing about our duty –“

“I know enough!”

“You know _nothing_ ,” he repeats, “Head filled too much with the fancy of humanity… distracting you from your own people!”

“Some days it feels like I know them better than my people!”

“They’re like plankton, Castiel,” Charles tells him, “Why do you spend your time defending such meaningless creatures.”

Castiel’s mouth falls into a grim line. “Even the smallest beings like the plankton are necessary for life to continue.”

Charles growls, spooking not only him but Hannah and his entire entourage as well. He doesn’t flinch, but the sea horses spook themselves into a flurry of frantic whinnying. A few guards rush to calm them. Thunder sounds not from far off, the sound sparking a realization within Castiel.

His eyes widen and he backs away. His stare finds the trident, glowing brighter than before. “No…” He rushes away, back up to the surface.

“Castiel!” his father calls to him, “Castiel! Where are you going?”

He breaks through the choppy waves, watching in horror as the boat rocks violently, fighting the sudden disturbance. “No,” he mutters, “no no no –“ Castiel swims without thought, making his way over to the battered vessel. He doesn’t get far, tugged back against his best efforts. “What -?”

Charles holds him, dragging him back under the water.

“What are you doing?” Castiel asks, “The boat –“

“Will live or die by its own merits,” Charles tells him, “Who are we to interfere?”

“We interfered already by causing this storm,” Castiel yells, “ _You_ caused this storm.”

“No, Castiel, I am not alone in this,” Charles says, “You let your anger get the better of you as much as I did, the trident responds to your emotions as much as they do mine. Feeding off of them, releasing them out into the very ocean we call home.” His harsh brows unbend, smoothing out. “You may consider yourself grown but there is still much to learn. Like how unbridled actions have their consequences.”

“So we let them drown?”

“And then what?” Charles asks him, “There is nothing we can do for them than what we already have. Be grateful I don’t throw you away in the brig for the amount of laws you’ve broken today.”

Castiel feels an octopus wrap its tentacles around his heart and squeeze tight. “I can’t believe you –“

_CRACK!_

The noise was loud enough to draw Castiel’s attention away. He turns, finding pieces floating down from where the humans were. Castiel’s face fell in horror watching the vessel sink into the sea. “No…” Dashing again up to the surface, he breaks the water with a scream after seeing nothing but red heat and heaps bopping with the waves.

Numb, Castiel doesn’t notice his father join him. “Leave them be, Castiel,” he says, “humans and mermans are not meant to mingle. Let this day serve as a reminder to the dangers that wait if we do…”

Castiel wipes at his cheeks, uncertain as to why. His fingers brushed the damp skin while his tongue lapped at a droplet that crawled its way down. It didn’t taste any different than the salt he normally tasted.

“Come,” Charles says, “There’s nothing left for you here.”

He’s alone, staring as the burn dims and squashes into nothing. The water around him quiets and returns to its former peacefulness, the dark clouds that washed over the sky fading like they were never there. The sea holds only remnants of what once was there.

Castiel almost leaves, then, before a bit of splashing catches his eye.

A figure breaks out from beneath the tides, clawing its way out of a watery grave. It clings to a floating piece from what was left and releases a call that shakes Castiel to his core.

He makes his decision in the space between seconds. Castiel dives under the water, speeding over to the wreckage. Then, as fast as he can manage, he plows into the body and circles his arms around the body.

Castiel won’t have enough time if he wants to avoid his father’s suspicion. Thankfully there’s a small islet off to the right that he can drop the survivor off. He swims far enough until he can feel sand scraping against his bare chest. Letting go, Castiel spins and leaves before the human could tell.

Something makes him look back, though. Castiel peeks his head slightly out, eyes finding that of the human on the beach. It was scrambling onto the shore, coughing and shouting. Satisfied, Castiel sinks into the deep.

“I’m sorry,” he whispers, off to rejoin the others, “I’m sorry.”

* * *

He shouldn’t have been back. His father was generous before, only locking him away for two weeks in his room. And then the patrol surrounding him only doubled during the times he was out of the castle. By his father’s design, those few times were few and far between. There were other places he could have gone when he did manage to slip away. Castiel found himself always returning here.

The islet where he dropped the human off hadn’t changed much in the time he was gone. There was a strange structure built on the visible shoreline, along with a few other things. And the human, thankfully, remained.

He will admit that whenever his mind wasn’t forced into political matters, it drifted towards the human. Wondering after its well being, hoping he did enough to ensure its safety. Like the human was the pearl in the sky and Castiel the ocean, subject to its whims.

Even now, as it exits the structure, Castiel’s eyes lock on to its strange shape.

With no pressing matters to attend to, he had the time to fully observe a human in the wild. The first part that interested him is his fins. They were completely different from Castiel’s, with no shine to them. Instead of a fluke these strange barnacles hung from them. One day, hiding under the water, Castiel watched them wriggle around like the bits had minds of their own. In total Castiel counted eleven – ten at the bottom and one large part most likely used for steering. He had no idea how it would help, but appreciated it either way.

The human looked around his size and age, with a dusting of markings across his face and collar. His hair reminded him of the color of sand, and his eyes were as green as the kelp that grew plentiful in their domain. Although a more apt comparison would probably be the tall weeds that grew on the islet.

There was much to learn by observing the human. Castiel grew to understand them much more intimately in his studies. They weren’t that dissimilar to his own people even if physically there’s a stark divide.

Humans eat like they do, with their mouths. They rest, talk to themselves, and try to entertain themselves. One night Castiel heard a beautiful melody when his head poked out from the dark sea, transfixed. The words were more garbled than Gabriel when telling a story at dinner, but the notes and meaning struck a chord within Castiel. Slowly he made his way over to the rock outcropping he chose as his hideaway.

The human sung to no one, hunched over himself. It smiled, but not in any way that meant it was happy. He stopped thinking about humans as a whole and focused on the one in front of him. Silently asked if there was a family that might be missing him, if there was an empty hole in his community because he wasn’t there. After a few songs, Castiel couldn’t stand the grief and swam away.

He comes back to the moment when he sees the human disappearing behind the weed line. Castiel sighs, slumping onto the rocks. “Humans are as curious as I am, I suppose,” he noted one day after arriving to an empty beach, “The need to explore in their veins.”

Castiel debates leaving, then, since he had no way to know for sure how long it would be before the human would return. One time he nearly missed curfew waiting for the human to make it back. It was a night he would never forget, his heart like a crab trying to shed the shell of his chest.

He bides his time, giving the human a chance to prove himself before Castiel gave up. There wasn’t much to do with the human gone though, so Castiel arranges shells into different colorful patterns while he waits. He taps a yellow one against the craggy rock when a figure trudges out from behind a few green coverings.

Castiel leans behind the cover of his outcrop, curious as to what brought the human back so soon. It’s obvious when the human dangles something from his hand.

The amulet glows golden in the light of the volcanic vent, glittering; prettier than any pearl. He has never seen anything like it in his time. It’s a simple accessory, but with a captivating power Castiel can notice even from where he rests. So distracted by its wonder, Castiel ignores where he is.

“Wow…”

The human stiffens, beginning to turn towards him. Castiel dips back behind the rocks, cursing silently. He hopes the human will wave off his slip, but those are dashed when the rough and familiar timbre of the human’s voice calls.

The noise comes closer, the human advancing on his position. He dare not look up, not ready for the human to see him. A blush settles on his cheeks, Castiel embarrassed to have gotten himself into the mess to begin with.

It inches further and further towards him. Castiel creeps along the edges, glaring at his tail to not make a splash.

Rounding a corner in time, Castiel sees the human’s head duck past the rocks where he was. Finding nothing wrong, the human pulls himself up to his full height.

Even with the threat of discovery nearby, Castiel cannot think of any reason to leave yet. Still enraptured with the amulet, he lifts himself out of the water enough to watch the human examining it again.

Shrugging, the human places it over its head. Castiel frowns; uncertain why his skin pricks and bubbles when the amulet easily falls against its chest. But then the human bursts into a bright beam of light, startling Castiel out of hiding.

The human’s form is engulfed by the strange magic. Its body rises and swirling a mix of yellow, reds, and blues. There’s a large swell like a whale song, only the notes are too high pitched for it to be from the ocean’s largest child.

Soon enough, the light dissipates and the human falls back to the ground. Except what was unintelligible mumbling is now a clear language Castiel can understand.

 “What the hell? What the hell! Dean, how can this get worse for you – oh God what happened? Am I all here? Hands, face, tail – tail?  _Tail?!?_  Why do I have a tail?”

 “You have a tail?”

 The human whirls around to face him, his jaw slackening when his eyes meet Castiel’s. He jumps, backing away as much as he can by dragging his new form. “What?” the human says, “What’s going on? What happened? Who are you?”

 “I’m Castiel,” he says, “A merman. As are… as are you now.”

 They both glance away at each other and towards the human’s newest appendage. What once were two is now one, a perfect mirror to Castiel’s tail. Except where his was blue, the human’s tail was green.

        “So,” Castiel continues, smiling, “what’s your name?”


	2. Part of Your World

        Castiel waits for the former human to answer with what he hopes is a non-threatening smile. His expression doesn’t seem to aid in easing the new merman into their body. As the silence drags on Castiel notices the other’s tail flap ever more erratically.

        He frowns. “Do you… not have names?”

        The human blinks at him. “What?”

        “Do you not know what names are?”

        “I know what names are!”

        “Then why won’t you tell me yours?” Castiel asks, “Are names important to humans? Are they embarrassing –“

        “Dean.”

        Castiel pauses, leaning against the rock in confused interest. “Come again?”

        “My name is Dean,” Dean repeats, “it’s what you asked for.”

        “Dean,” Castiel tests the name out on his tongue, scrunching his nose up. “That’s an odd name.”

        “It’s a regular name – a _strong_ name for a man,” Dean tells him. Then, in a soft mutter, he admits, “Although I _was_ named after my grandma…”

        “Oh,” Castiel says, “you’re a _male_.”

        “Yes!” Dean squints at him, “How in the hell did you _not_ know that?”

        “I was unsure if there existed a concept of gender in humans – the line already blurred so much for my people.”

        “Well if you took a look at my –“ his hand slaps at his tail, jaw dropping in horror, “My dick! My dick’s gone, too?”

        “Your… dick?” He stares at where Dean’s hands scratch at his scales, realization dawned on him. “Oh! Your reproductive organ… I didn’t know humans - it’s not gone it’s hidden.”

        Dean doesn’t hear him, still lost in his panic. “How can this get any worse?”

        Castiel pouts. “How is this worse?”

        Dean scoffs, “Do you have any idea what it’s like to have a tail?”

        Rolling his eyes, Castiel waves his fins above the water at Dean. He chuckles when he notices the color drain from Dean’s face, the marking much more obvious now then they were before. “All my life,” Castiel says, “Because I’m a merman, like you are.”

        “But I’m not,” Dean hisses, “I’m a – I _was_ a human!”

        “And now you’re not.”

        “Why, though, _why_?” He starts hyperventilating, clawing at his neck. His lips turn blue, and Dean rasps out for help.

        “Oh – _oh!_ ” Castiel panics, reaching out for Dean, “You need to get in the water! You’re suffocating!” Dean bats his hands away at first, still choking. Castiel growls, “Don’t fight me on this, who’s the more experienced merman here?” There’s a moment of slight hesitation before Dean accepts his touch. Slipping his hand into Castiel’s, he lets the other tug him into the water. Dean falls in with a splash, flipping around wildly.

        “Drowning!” he coughs, “Can’t… kick…”

        “Kick?” Castiel asks, “Why would you  - what’s – nevermind… “ He wraps his arms around Dean’s torso, pressing back to chest. “Follow what I’m doing… come on.” Castiel pronounces his movements, teaching Dean to quickly tread the water with his tail. When the adrenaline passes. Castiel feels the other sag against him like dead weight. But he doesn’t hold him up for long, as his tail hits against Castiel’s slowly.

        Soon enough, Dean can swim without aid. Castiel lets go, Dean’s arms shooting out to the side almost immediately. It’s a strange sight, but Castiel shrugs at his choice. Whatever helps him stay upright.

        “That’s… better,” Dean says, “Like I can breathe.”

        “Probably because now you can,” Castiel tells him, “We’re not supposed to be out of the water for too long.”

        “Until a few moments ago I could,” Dean sighs, “Forgive me if I’m struggling.”

        Castiel nods. “It’s okay… at least now we know the transformation wasn’t superficial. The magic you’re playing with is much more serious than a simple glamour.”

        “Magic?” Dean chuckles, “Of course… mermaids exist, so why not magic!”

        The remark causes Castiel to bend his brow at a curious angle. “Magic has always existed in this world. Has humanity not been alerted to its presence? Do they…” his voice grows smaller, “Do they not even know of us?”

        Dean looks even more uncomfortable than when he did after the transformation. “I mean… little kids believe in you guys. And a bunch of women who buy stuff off of Etsy. But I think that’s it… you’re all supposed to be _fairy tales_. Stories people and Disney tell to entertain and make a quick buck.”

        Castiel deflates, disappointed that his people were reduced to nothing more than a story in the human consciousness. It makes Dean’s unease all the easier to understand. He forces a grin on to his face. “Well… now you know both are real things. Congratulations!”

        The mock cheer does not aid to improve Dean’s mood. Instead he sinks into the water, chin disappearing into the water. “So I’m stuck like this?” he asks, “Some kind of reverse Little Mermaid?”

        “I… I’m not sure what that means,” Castiel says, “But it’s not that bad. My people are…” He can’t finish that truthfully, instead placing a comforting hand on his shoulder, “There’s a lot to explore.” He finishes lamely.

        “I wish I never did whatever made me turn into this.”

        Castiel eyes the amulet around Dean’s neck, the only part of him that hadn’t changed. “Well, maybe the next time you spot some jewelry you won’t put it on.”

        “What?” Dean tracks Castiel’s gaze, eyes widening. “Shit, you think it did this?”

        “It’s the only thing that makes sense?”

        “So if I take this off, I’ll be back to normal?”

        The logic makes sense, even with a force as tricky as magic. While they were hard to control or predict, they followed their own set of rules. Castiel had read about different enchantments wearing off when the objects tied to the spell were removed. Still, the idea of Dean returning to his normal form sends an icy chill through his veins.

        Castiel grabs at Dean’s wrist before he could touch the amulet.

        “Hey,” he grumbles, “What do you think you’re doing?”

        “Don’t take it off.”

        “Why not?”

        “If you do, you’ll go back to your former body,” Castiel explains, “And we won’t be able to communicate.”

        “But I’ll have legs,” Dean says, “And not need to breathe water. Oh – and I’ll have _legs_ ! I’m flattered you want to keep talking but I’ve had my fill of _fish_ for a _lifetime_.”

        Dean tugs himself free from Castiel’s hold. Thinking fast, he tries latching onto anything that might keep Dean from shifting. He turns to the vast ocean in front of him, searching it for an answer. Even if he can’t understand why he might want Dean to stay in his merman form, a sheer terror roots itself in his heart at the prospect of facing a human again.

        “Please, don’t –“

        “Seriously, there’s nothing you can say that’ll convince me to keep this on.”

        “What if I –“

        “You don’t have anything I want.”

        “Not even a way home?”

        Dean pauses, eyeing him warily. “What?”

        “I doubt this small enclave is where you originated from,” Castiel starts, “And you seem sad and wistful… like you’re missing something. This island is not where you wish to be.”

        “And you know where I _do_?”

        “The oceans are _my_ home,” he says, “I’m sure I can navigate us both to your shores.”

        Dean scoffs. “Us?”

        “You need me,” Castiel continues, “I doubt even if I drew a detailed map you’d be able to follow it safely. The deep has many dangers the likes with which you don’t know and would rather not face.”

        He rests the amulet back against his chest. Dean considers Castiel’s offer, obvious by the pout of his lips and arch of his brow. Castiel smoothens his face into pure charity, showing Dean there is no ill will in his intentions.

        In fact, it’s the best course of action for both of them. Dean will get to reunite with his family, if he had one. And Castiel can make the tides of his conscious rest easy knowing he helped this poor unfortunate soul, especially considering the part he had to play in the human’s ‘accident’. If he learns a few things about humans along the way… it’s only an added bonus.

        “I… I would like to go home,” Dean sighs, trailing his gaze over the same blue waters Castiel looked at moments before. “You can lead me back there?”

        “Tell me where you intend to go,” Castiel tells him, “And I’ll guide you there safely.”

        He gnaws on his lip, tapping at his chest. Suddenly, his hands flail in the water and splash a few droplets Castiel’s way. “Fine,” he says, “Whatever. I guess we’re doing this.” He points behind him, “We came from this way. Me and my… _crew_ , we’re all from a small town off the southern coast of California.”

        “Cali…fornia?”

        Dean sneers. “You sure you know where you’re going?”

        Castiel blushes, swimming past Dean in the direction he pointed. “Of course. We do not call it California though.”

        “What do you call it?”

        “…Land.”

        He hears Dean sigh behind him, splashing in his wake. “I got a nagging feeling I’m gonna regret this.”

        Castiel rolls his eyes, skin tight with Dean’s expectations. Unwilling to be scrutinized further, he plunges into the ocean to swim better. However he doesn’t get far, the familiar sound of someone diving next to him had never come. Glancing around, Castiel spots Dean’s tail and not much else from him.

        He resurfaces, startling Dean. “Crap!” Dean yells, huffing, “Why’d you leave?”

        “I didn’t leave.”

        “You weren’t here a second ago!”

        “I went underwater,” Castiel tells him, “It’ll be faster, safer – _easier_.”

        Dean darts a fearful gaze at the ocean, swallowing past a shell in his throat. “You sure?” he asks, “Couldn’t we just tread water up here under the sun?”

        “What is the sun?”

        The other merman chuckles, “Sure, you don’t know what the sun is…” At Castiel’s unflinching stare, Dean winces. “You really don’t know what the sun is?”

        “I know about sons,” Castiel says, “I _am_ one.”

        “No, no that’s not – that’s not what I’m talking about.” Dean points up towards the large vent above. “ _That_ ’s called the sun – it’s spelt differently.”

        “That is… _confusing_.”

        “You not knowing about the sun is confusing. Next thing you’re going to tell me you don’t know what the moon is, too.”

        “…The moon?”

        Dean slaps his face over his eyes, cursing. “With each passing moment I feel my confidence in you slipping further and further away.”

        Castiel growls; spinning around harshly, his tail no doubt splashes at Dean. “You don’t need me for my knowledge of human things… my talents lie elsewhere. Now come, underwater.”

        “But what if I need to breathe –“

        “You’ll be able to breathe well down there,” Castiel smirks, “You are a _merman_ after all.” He dips back down, not too far. Enough to watch Dean’s tail twitch as he works through his thoughts. After a short wait, Dean joins him under the sea.

        His eyes are shut tighter than a clamshell, as is his mouth. With puffed up cheeks, Castiel chuckles at the sight of him. Laughter draws Dean’s eyes wide open. He gapes at Castiel, and then swims in a tight circle while examining the sea.

        “I can hear you, I can – I can _see_ ,” he says. Gasping, he freezes and stares at Castiel again. “I can talk and move my mouth and I’m not _drowning_!”

        His joy infectious, Castiel’s grin stretches farther the more he watches Dean enjoying himself. Now acquainted with the ocean, Dean’s timidity sheds as he swims around the area. Dean dashes over to a school of fish, reaching out as if to touch. Before he could they break apart and swim away.

        Dean’s innocent play refreshes Castiel’s spirit, haven’t seen anyone act so free like this since he was a babe. So much changes when a merperson grows older, the weight of responsibility weighing heavily on the soul like a hard shell. Unable to wriggle free and enjoy life, be present in the moment. Even in a different body, Dean carries that human independence fiercely within him; makes Castiel yearn for some of it himself… among other things. His eyes trace Dean’s form, tongue peeking out from behind his lips.

        Shaking his head, Castiel breaks from the trance. He calls to Dean. “We best get going,” he says, “There’s much more to see on our journey.”

        “Right, right…” Dean moves closer to him, gesturing ahead of them. “Why don’t you lead the way?”

        “Of course.”

        They push forward, swimming side by side. Castiel paces himself, knowing Dean’s limitations. While he learns fast, there’s still awhile to go before he can reach the level most merpeople are at around their age.

        “Hey, Castiel?”

        “Yes Dean?”

        “Not that I’m ungrateful or anything…” Dean sighs, biting his lip. “Why are you doing this? Helping me?”

        Castiel frowns, gaze focused ahead of him. “Because it’s the right thing to do. You’re separated far from your people, your family… your _home_.”

        “What about you?”

        “What about me?”

        “Don’t you have a family?” Dean asks, “A home? Wouldn’t your time be better spent with them instead of me – a _stranger_?”

        Castiel nearly forgot about his own worries. Dean’s casualness brings them back full force. He stills, Dean passing him with his strokes.

        There is much at stake with Castiel’s mission. If his father were to find out… Dean could be in worse trouble than when Charles caught Castiel studying his ship. Even now, Castiel knows he’s been away from home longer than he should.

        “Castiel? Castiel… _Cas_?”

        He blinks back into awareness, Dean much closer than he was earlier. “What?”

        “You okay there? Kinda zoned out there…”

        “No, no…” Castiel frowns, skewing his head to the side, “What did you call me?”

        “…Cas?”

        “What’s that?”

        “It’s a nickname,” Dean explains, “You… don’t have nicknames?”

        “What’s a nickname?”

        Dean sighs, rubbing at his jaw. “It’s like a shortened version of your name. Castiel becomes… _Cas_.”

        Castiel rolls the name around on his tongue. “Cas… huh. I can see the merits of a shortened name.”

        “…Merits?”

        “In danger,” Castiel explains, “it’s easier than shouting Castiel. Do you have a nickname?”

        Dean chuckles, shoving at Castiel’s shoulder. “Dean’s already short enough…” He glances at him from out the corner of his eye. “So we’re not going to talk about where you just went?”

        “I didn’t go anywhere.”

        “Nevermind… let’s shake a tailfin.” Dean darts ahead, Castiel pushing himself harder to catch up.

        He knows that there’s no going back now. Seeing this through to the end is what he must focus on. Putting his family and duties in the back of his mind, Castiel prays that’s where they stay. And that nothing will come up that will endanger them.

* * *

        From Dean’s earlier wonderment, Castiel was surprised how silent their time together has been. After the shock wore off, Dean shrunk back into himself. Castiel couldn’t find a way to break the quiet, so many questions inside his head he couldn’t begin to choose where to start.

        They swim past a pod of dolphins when Dean finds his voice again.

        “So,” he starts, “can you speak to fish?”

        Castiel sighs. “Yes… but probably not how you’re thinking. We can communicate but we’re not so sure if they understand. And if they do, they don’t listen… however if you spend years training a certain animal like a seahorse or a turtle – even a swordfish – they make for great pets.”

        Dean huffs. “Well that’s unfortunate.” He snaps his fingers, chuckling. “What about whales? They’re technically mammals, not fish!”

        “No one can speak _whale_ , Dean.”

        “I can.”

        Castiel raises a brow. “You can?” Dean hums, lips curling in amusement. “How does one ‘speak whale’. Is it a _mammal_ thing?”

        “Nah, it’s real simple, you just gotta –“ he clears his throat, puffing out his chest, “ _taallllk liiiike thiiiiiis Caaaaasssss_!” His voice rose and fell like the tides, mimicking a bastardized way whales communicated. Castiel would have been fooled if Dean hadn’t snickered the entire time.

        “That’s not funny, Dean,” Castiel scolds, “Whales have beautiful voices – I should know. A troupe of them sang for my Molting Day Ceremony.”

        “Molting Day?” Dean winces, “What’s that?”

        “It’s a great tradition for my people,” Castiel explains, “When it’s been eighteen cycles since the time you are born, you’re officially inducted into the community as an adult. It’s the beginning of the rest of your life, when you’re supposed to leave childish things in your past.”

        Dean chuckles, “For us that’s called high school graduation. I never went to mine.”

        Castiel startles, eyeing Dean with a worrying gaze. “What?” he asks, “Were you sick? Did something come up?”

        “No, no I just… well I never finished high school,” Dean tells him, “This… place where you go to learn. Where I’m from there’s this thing called ‘mandatory education’, and it ends after high school. After that you either enter the workforce or continue learning at other, more fancier schools. I was never that good at it so I went ahead and did this… _thing_ that made it so I could skip my last year. Then I started making money so my brother could have enough for whatever college he went to.”

        Castiel nods, still somewhat lost. He latches onto something he could understand. “You have a brother?”

        “Yeah,” Dean says, smiling the easiest grin he’s seen on the other’s face yet, “Sam. My little brother… he got all the brains while I was stuck with the handsome face and people skills.”

        Castiel makes a thoughtful noise. “So he’s a hideous shut-in. How unfortunate…”

        Dean stumbles, unable to continue swimming because he’s laughing too much. His entire being shakes with joy, curling in on himself from the raucous giggles coursing through his body. Castiel slows down and watches him curiously.

        “Oh man, you sure do take everything so literally,” Dean chuckles, wiping at his eyes, “No, he’s not that bad looking. I mean, if you can get past the mop of hair he’s grown. And he’s a bit of a nerd…”

        “I don’t know what that means,” Castiel sighs, “ _Nerd_ …”

        “Geek? Lame? Not cool…” Nothing he says makes any sense to Castiel. “Even though I can talk to you there’s still a language barrier. Don’t you have brothers or sisters who try and… I don’t know, embarrass you by making you seem _worse_ than you actually are?”

        “All the time,” Castiel says, “My brother Gabriel says I take things too seriously – that I’m as lively as chum. And Lucifer had a habit of always telling me I was a slow swimmer, even though I’ve bested him in races for six cycles in a row! Those are just two of my siblings…”

        “Come from a large family?”

        “Yes, and unfortunately I’m the youngest out of all of them.” He crosses his arms, lazily flipping his fins. “The last egg laid before our mother…”

        It’s not something he’s comfortable talking about. Castiel barely remembers what his mother was like, having hatched days after she was lain to rest. He was told he had her eyes, sometimes thinking that she’s seeing everything he does. The thought passes that maybe she’s watching him now, and he hopes she would approve of his actions.

        Dean places a hand on his shoulder. “My mom died young, too,” he tells him, “a little after Sammy… it’s been just him and me, and my dad… plus Uncle Bobby.”

        “Your father,” Castiel starts, “do you get along? I mean, is it… customary for humans to disagree with their parents?”

        Dean chuckles. “It’s completely normal and _expected_. I mean… if you met my dad -”

        “What’s he like?”

        He forces a smile onto his face, more like a wince than anything. “He’s… rough around the edges; surly. Especially after he’s had a couple of drinks. Dad and _Sam_ were the ones who fought the most, at it almost every night until Sam moved out. There were other things he and I didn’t agree on… but we kind of let it drift, better to not speak about it than bring it up and ruin a day. Although maybe that’s why we haven’t been talking for awhile…” Dean looks lost, unsure of what to say next. He already seemed surprised to have shared as much as he did.

        Castiel reaches out to him and squeezes his wrist. “Maybe it’s a little brother thing. My dad and I fight whenever I don’t have the energy to tune him out… I wish we wouldn’t though. I can still remember being young and thinking the world of my father… listening to him like he knew everything. Now I realize he has a very narrow view on things – especially _humans_.”

        “He not a fan of us?”

        “Not many of my people are,” Castiel says, “It’s forbidden to go up to the surface, to talk with one of you.”

        Dean inches closer worryingly. “Shit… you’re not gonna get in some serious trouble for helping me, are you?”

        Castiel smirks, glancing at the amulet. “Why would I? You’re a merman, aren’t you?”

        He rolls his eyes, breaking Castiel’s hold on him. “Not for too long…”

        The deadline pokes at Castiel’s heart, hurting it in a way he’s never been pained before. “Right,” he says, pushing the feeling away, “We should carry on. So besides your brother, father, and Uncle… do you have any other family?”

        “Well, there is my Baby –“

        Castiel’s breath hitches, eyes bulging out from his head. “You’re a parent?” he asks. Already the images float into Castiel’s mind, of Dean with a little child cradled in his arms. Cooing at the creature, maybe another by his side. A faceless amalgamation of different humans he’s seen over the years, someone who would help him raise his child.

        Dean chokes on water, coughing. “No, no,” he says, frantic, “Not a – I don’t have a kid, Cas. I’m not – it wouldn’t.” Breathing deep, Dean tries again. “I’m talking about my _car_.”

        Castiel blinks at him. “A… car?”

        “You know,” he moves his hands around in a circle, only further increasing Castiel’s confusion. “You don’t have cars? How do you get around when you’re tired from swimming?”

        “Well there are chariots,” Castiel tells him, “drawn by seahorses… is that like a car?”

        “Something like that,” Dean sighs, “Figures you wouldn’t see a car, they can’t really go in the water.”

        “Wait, if a car can’t go in the water how did you get so far away?”

        “By boat.”

        “Boat?” Castiel parrots, “How many different vessels do humans have?”

        Dean holds out his hand, counting. “Well we have cars, boats, motorcycles, bicycles, mopeds, buses, trains, airplanes – although really those are untrustworthy if you ask me – and…”

        “Stop, stop,” Castiel says, “Are humans lazy?”

        Dean snorts. “Yes, but not because of all that. If we walked everywhere things would take so much longer. Everything else makes things… _shorter_.”

        “There is so much about humanity that is confusing,” Castiel says, swimming away, “…it thrills me!”

        Dean hurries to catch up. “So,” he starts, “back then you looked kinda… _disappointed_ to hear I had a kid.” There’s a strange note in his voice, as if he’s seeking a different answer than the obvious one Castiel would give.

        “It was a shock,” Castiel says, “And made me feel even worse for your situation. To have pulled you away from your child and your… wife?”

        “Nope! No wife,” Dean cuts in too quickly, blushing, “I mean – I wouldn’t… wives and me don’t mix. Kinda not interested in their whole… deal…”

        “Oh, so you’re against mating rituals,” Castiel surmises, “I happen to agree with you. They’re so ancient… having your spouse picked out for you based on breeding and class, being told who to spend your life with –“

        “Shit, no, Cas,” Dean sighs, “that’s… you don’t marry for love?”

        “Love?” Castiel asks, “That… hmm… I’ve never thought about how love would play into these sorts of partnerships.”

        “Holy shit, Cas,” Dean says, voice deadly serious, “You’ve never… does no one marry for love?”

        “No one that I’ve ever known.”

        “That’s… really sad,” Dean tells him, “I couldn’t even imagine… at least when my ma was alive she and dad were the real deal. I always knew that if I were going to get married that I’d want it to be with someone I love.”

        “But you just said you and ‘wives’ do not ‘mix’.”

        Dean groans. “Because I’m not in the market for a wife, Cas. I’m looking for a… y’know… _husband_.”

        Castiel frowns. “And if you ever want kids?”

        “There’s always adoption.” Dean stops, nervously glancing over at Castiel. “I… I should have asked, first. Is there like… anything _against_ that kind of stuff in your culture? Merpeople of the same gender being… _intimate_?”

        “No, no,” Castiel answers, “we don’t hold any judgment on who another person chooses to engage their time with… as long as an offspring is produced from a mating than really no one cares. One of the benefits, I suppose, to loveless bondings.”

        “…Apparently.” Dean scoots closer to him, skittish. “So… no _other_ reason you might have reacted like that?”

        “None that I can think of.”

        “Really?” Dean asks.

        “Is there a certain way you _wish_ I would have?”

        Dean shakes his head, smiling sadly. “Nah, just… it seemed more layered than it actually was s’all. Never mind.” He folds in on himself, eyes locked on a far off point below them.

        Castiel wants to press the issue further, but decides against it. They’ve already lost enough time in their exchange of information. And while Castiel learned a great deal, it would have been better if they had their conversation while moving.

        “Very well, then,” Castiel says, “We should carry on.” He nearly leaves until he sees Dean remains frozen where he is. “Dean?”

        “…Would you look at that?” Dean murmurs, “What is it…?”

        “Dean?” Castiel repeats, worried. He nearly calls for him a third time when Dean begins swimming down further into the depths of the ocean. Zooming into it, Castiel waits a beat before swimming after him.

        The closer he gets, the more he sees what Dean does. Gasps when he notices the flashing light hiding in the darkness. “Dean, no!” His hand shoots out, reaching for the other. Dean’s tail flips wildly, making it difficult to grab. Castiel does, tugging him to stop.

        “It’s so pretty…” Dean says, arms stretched far to grab for it.

        “No, Dean,” Castiel says, grunting, “It’s… it’s not what it seems…”

        The light gets brighter, closer. Castiel squints, not looking directly at it so as not to fall under the same spell Dean was. He knows he doesn’t have much time to get them out from there. Thinking about the danger that might befall them – befall _Dean_ – sparks within him an incredible source of power that gives Castiel newfound energy.

        Slipping his other hand around Dean’s tail, Castiel drags the other up and away. Dean struggles, whining about how he wants to go back. “Trust me, Dean,” Castiel tells him, “It’s for your own good… let’s put some distance between us and…  _that_.” Glancing back, he can see the light blink and fade into nothing, descending back into the murky depths to wait for another unsuspecting prey.

        Dean quits his squirming soon enough. “Cas?” he asks, “What… why’re you holding me like that?”

        “Thank Poseidon you’re back to yourself,” Castiel sighs, letting go, “I almost lost you back there…”

        “What happened?”

        “You were mesmerized by an angler fish,” Castiel explains, “They’re creatures with these hypnotic lights on their –“

        “I know what an angler fish is, Cas,” Dean scoffs, “And really? That so didn’t happen.”

        “It most certainly did!”

        Dean blushes, puffing his chest out. “Even if it  _did_ , what’s it matter? They’re like… small?”

        “Dean,” Castiel says, “an angler fish is a ferocious beast. Larger than  _two_  of you. It can swallow you up with no effort at all.”

        Silence. Then, “… _Oh_.”

        “If I hadn’t rescued you…” Castiel shudders at the possibility of Dean not being alive, chest tightening. “You need to be more careful,” he says, “I might not know much about your world… but you know even less about mine.”

        “Don’t have to tell me twice, Cas,” Dean hisses, “Won’t have to babysit me…”

        The frown on Dean’s face doesn’t sit right with Castiel, either. Hoping to improve the mood, Castiel swims up beside Dean and pokes him in the side. “And… try not to get distracted by any more shiny things.”

        Dean splutters, causing Castiel’s small giggle to become a full laugh. When the noise dies down, he finds Dean watching him with a tiny grin of his own. Castiel skews his head to the side. “What?”

        He shakes his head, “Nothing. Come on… let’s move.”

        Castiel shrugs, but follows. It’s been a whirlwind of a day so far, but Castiel knows there’s more to come. He’s already seen and learned so much… not just about Dean’s world. There’s something about  _Dean_  that makes Castiel’s head spin, and he wants to know what that is.

        Although, he already feels like he knows why. If only he could put a name to it.


	3. Duty to What?

        “…So there’s no such thing as a shell bra?”

        Castiel sighs, lazily swimming next to an impish looking Dean. “We do not wear those kinds of shells,” he tells Dean, “they are too tough and stiff… besides, they serve us better as tools.”

        Dean nods, thinking. “Then I guess it’s boob central where you come from isn’t it? All the bits floating and whatnot”

        “Why does this bother you?” Castiel asks. “Do humans cover themselves in hard, constrictive shells?”

        “We cover ourselves,” Dean explains, “but they’re not always… _hard_.”

        He rolls his eyes at the absurdity of humanity. In his mind, Castiel marks a tally for another concept from Dean’s world he doesn’t understand. It began a while ago, when Dean made mention of something called pie.

        Pie. A delicious treat, Dean said. Gooey and flakey and filled with love, _baked_ in a contraption named an _oven._ From what Castiel understood it was like a mini volcano people kept in their homes. Why anyone would think that’s a safe and smart idea, Castiel cannot begin to fathom.

        From there he realized humanity was more complicated then the little boats he watched.

        Castiel tunes back into the conversation as Dean waxes on about something called ‘flannel’. His eyes blink heavily, and his tail struggles to propel himself forward. Dean shoots past him unknowingly. It’s a beat before Dean swims back wearing a concerned frown.

        “Cas,” he says, “you all right?”

        He shakes his head. “I’m tired, Dean. We’ve been swimming for quite some time…”

        “Yeah, but I’m sure we’re close –“

        “I… I think we still have another day,” Castiel tells him, yawning, “And I’ll be no use if I’m swimming with my eyes closed.” Dean huffs and crosses his arms, waiting. But Castiel fixes him with a fierce glare, not willing to budge. In the end Dean loses, a yawn breaking through his own annoyance.

        “You got a point,” Dean mumbles, rubbing at his eye, “Fine. What do you got for beds around here?”

        Castiel searches below, eyes darting around until he spots what he needs. “Follow me.” He moves without hearing Dean’s answer, trusting the other to follow him.

        The closer he gets, the easier it becomes to distinguish the fish circling the anemone. They’re adorable clown fish, and they haven’t noticed Castiel. Pooling at his reserves, he musters up the energy to dart forward and snatch four of them – two in each hand and the other in his mouth. The school scatters from the anemone as Castiel tears into the fish with fury. He devours them in the blink of an eye, spitting the skeletons out.

        Clown fish wriggle in his hands aware of their fate. However he doesn’t eat them. Instead he turns around and offers them to a horrified Dean. Castiel’s head tilts to the side, confused. “What?” he asks, a piece of scale flying out from his teeth.

        “What?” Dean scoffs, “What! You just ate Nemo and his dad!”

        Castiel frowns. “These fish do not have names, Dean. None that we know.”

        “That’s not what I –“

        “I was hungry,” Castiel explains further, “Do humans not eat fish?”

        Dean blanches, glancing away. “…We do –“

        “Then why do you look so troubled?”

        “Well, it’s…” Dean sighs, sinking against a rock, “the way you did it. I guess seeing you claw into those fish reminded me that you’re not really… _human_ . That I’m… not _human_.”

        “Of course. I’m a merman –“

        “I know Cas, I _know_. Still… wasn’t expecting you to turn into a shark then and there.”

        “What did you think we ate, Dean?”

        Dean shrugs. “Seaweed? I never really… I figured you wouldn’t eat the fish because they’re your friends and everything! Ariel had Flounder… Aquaman could talk to fish…”

        “Some creatures we consider pets, Dean,” Castiel says, “But if we enforced such a strict diet we’d _die._ Seaweed isn’t a meal… it’s _garnish._ ” He holds the fish out to Dean, “Come on, why don’t you eat?”

        Dean blanches, biting at his lip. “Raw?”

        “Is there any other way?”

        Castiel can tell Dean considers his meal very carefully, bubbles practically spilling out from his ears. A gurgle interrupts his contemplation, and Castiel knows what his decision will be. “Well,” Dean sighs, “guess sushi ain’t the _worse_ …”

        “Pardon?”

        “Never mind,” Dean says, hands in front of him, “why don’t you give me the fish.”

        He places them in Dean’s hands, keeping his own there while Dean’s remain flat and limp. Their eyes meet, and something flashes behind Dean’s eyes briefly.

        Dean clears his throat. “Cas?” he starts, cheeks dusted red, “What’re… you can let go.”

        “No, I can’t,” Castiel says, “not until you have a tight grip. Otherwise they’ll slip away.” He hopes Dean won’t argue, too tired to force Dean into following. If the fish escape he won’t chase after them. Dean is a grown merman, he can catch his own food. But he doesn’t have to if he does what Castiel says.

        Dean’s hands hold tight, and Castiel struggles to free himself. When he does, Dean’s fingers squeeze the clownfish.

        “Good,” Castiel says, bringing his empty hands to his mouth, “Now shove them in and bite fast. If you get the head that’ll stop them from wriggling around.”

        “I think I got it.” Dean brings the clown fish to his lips, eyes closed. He mumbles something Castiel can’t hear before chomping down on the fish. Chewing slowly, Dean pauses as his eyes spring open wide. Then with a renewed gusto, Dean crams the rest of the fish into his mouth before repeating the process with the second. His fingers disappear behind his lips as he sucks them clean. “Whoa,” he says, “that was… tastier than I thought.”

        “Glad to hear it met your satisfaction.”

        “Would it be crazy if I said it tasted like chicken?”

        “…What’s a chicken?”

        “…Never mind.” Dean slides further against the rock, slouching on it. “Hey,” he says, “not that I’m ungrateful or shit for the snack, but I thought you were searching for a bed?”

        “I found one,” Castiel tells him, “The snack came with the bed.”

        “What?”

        Castiel drifts over to the anemone, gesturing to it. “This is our bed.”

        Dean winces, “The wiggly fingers?”

        “Anemone,” he sighs, “They’re quite comfortable and refreshing to sleep in. Unfortunately we can only grow enough to use as pillows but… out here, they grow large enough that we can easily fit on them.”

        “Pillows?” Dean smirks, “Then what do you use as the actual bed? Giant clam shell?”

        “Like I said Dean, shells are _tools_ – sometimes _accessories_ . They aren’t _bras_ or beds.”

        “Joke, Cas,” he sighs, swimming up onto the anemone, “ _Sarcasm_ . Do they not have it where you live?” Dean slowly lies on the bed, squirming. “Tickles but… _nice_. Like magic fingers.”

        Castiel ignores the last comment, joining Dean on the bed. “We do… although, I will admit to have struggled with it in my life. I’ve never really gotten sarcasm, which at times both delighted and exasperated my family.”

        “Really?” Dean focuses on his hands, twiddling thumbs across his stomach. “Huh…” He seems uncomfortable, which worries Castiel as it goes against previous statements.

        “Is this not a suitable bed?” Castiel asks, “If not, I’m sure we can find –“

        “No, no it’s good, I…” Dean trails off, darting his gaze to Dean’s and then immediately dropping it. “I…” His sentence dangles like a hook, and taunts Castiel as it hangs out of reach. “It’s nothing.”

        “Is it? Dean –“

        “When I was younger,” Dean starts, a small smile on his face, “Back before my dad was… who he is now. When my mom was still alive, she’d tuck me in and she’d… she’d sing me a lullaby. It’d change from time to time, but whenever I was feeling low she’d always go with ‘Hey, Jude’. Then she’d kiss my forehead and… and tell me that no matter what happens – no matter how bad I feel – that there’s always someone looking out for me. She’d say it was angels up in Heaven…”

        “Angels? Heaven?”

        “It’s where we go when we die,” Dean explains, “People believe in it… when our bodies stop working this other part of ourselves… a soul… drifts on up to this place beyond the clouds. Angels are kind of like the caretakers of this place… made by God.”

        “Poseidon?”

        “Nah, nah… ours is just called God. Well, my family called him that... or her. Other people have different names for them.”

        Castiel nods. “That is… a comforting thought.”

        Dean looks at him. “Where do merpeople believe they go when they die?”

        He hums, frowning. “We don’t really ‘go’ anywhere, Dean,” he says, “When we die we return to the sea that birthed us. Our bodies become the salt and water that flows through all life… and once more we are reunited with everything and nothing.”

        Dean’s jaw hangs. “That’s… a really interesting way to think about it.” He turns, gazing out at the ocean. “Before this whole adventure… I never really thought about the ocean more than what I saw. What I didn’t know wouldn’t hurt me, I guess. But after all I saw… I think maybe we got it wrong.”

        “Hmm?”

        “I don’t think Heaven is above,” Dean tells him, “I think it’s down here. It’s so beautiful… and everything around us is amazing…”

        Castiel’s head tilts to the side, studying Dean. “Not that I don’t appreciate your opinions but… what brought this on?”

        Dean blushes, staring at Castiel from the corner of his eye. “Laying here I… I feel as safe as I did back when I was a kid and had a mom to tuck me in at night. Like maybe…” his fingers drum across his bare chest, “she was right, and that I’ve always had an angel watching over me.”

        Castiel’s face heats deliriously, his chest beating faster then he’s ever felt it go. “Oh,” he says, “that’s… _nice_?” His mind races with a flurry of meaningless words, nothing fitting to describe the sensations rushing across his body. In his confusion he focuses on the sound of Dean’s tapping.

        Annoyed, Castiel snatches Dean’s hand and stills the movement. Dean chokes on the water. “Cas?”

        “We should sleep,” Castiel tells him, “we still have a long journey ahead of us.”

        Dean nods. Shifting, he rolls onto his side to face Castiel. Castiel does the same. As he lets his consciousness drift away with the gentle underwater tides, Castiel realizes that he still holds Dean’s hand.

        He doesn’t let go. 

* * *

        Dean finds joy in the simplest of activities. Castiel barely noticed when the pod of dolphins swam by them. They were chaotic tricksters that visited Castiel’s home often – usually to chatter and play with Gabriel. He learned to ignore them at an early age. Dean, however, watched with awe as they passed. Then without notice Dean sped off after them.

        Castiel shouted after Dean’s green blur, the only response he received were loud whoops of excitement coupled with the dolphins’ squeaking.

        After a lengthy chase that dragged them off the path, Castiel managed to drag Dean away from his new friends.

        “What was that?”

        Dean apologized, laughing, “I’ve never been this close to a dolphin – never even _seen_ ‘em this close…”

        Castiel wanted to say that it’s nothing special – how dolphins are as common as the tides. But after catching his breath he saw Dean’s gummy smile and twinkling eyes and how his tail spun round and round in imitation of a whirlpool. He couldn’t muster up the annoyance from before.

        “Next time,” Castiel said, mirroring him with his own grin, “don’t get too far ahead of me, or you’ll get lost.”

        As they swam back to where they were, Castiel made note of the wonder etched across Dean’s face. How easily he could forget that Dean hadn’t always been a merman, and simple occurrences were anything _but_ ordinary to him.

        Now Castiel stays attuned to his surroundings, making sure to point out anything that might brighten Dean’s face once more. Along their journey they had seen a parade of jellyfish floating by, a friendly great white, and a few whales migrating along their path.

        When they happened upon the family, Dean broke into his antics once more. He waved and hollered, speaking to them in the bastardized tongue he used on Castiel.

        “I don’t understand why you think that’s how whales speak,” Castiel said, “It’s wrong.”

        “Man, Cas, the ocean might have a lot of things… but children’s entertainment is not one of them.”

        Dean didn’t explain further, instead shoving at Castiel and lazily swimming away. Castiel follows him, watching in amusement. However it slowly shifts as he spots something hidden behind a ridge.

        “Dean!” Castiel calls to him, drawing his attention, “Is that…”

        “Cool!” Dean hurries over to Castiel’s side, squeezing at his wrist, “I’ve never seen a ship like _that_!”

        “What kind of ship is it?”

        Dean squints, dragging his gaze across it. When he spies a ragged, black piece of seaweed drifting with the tide, his hold on Castiel’s wrist becomes too tight. “Awesome!” he cries, “So cool like, seriously –“

        “What is it, Dean?”

“It’s a _pirate_ ship, Cas!”

        “Pirate… ship?”

        “Yeah! They sail the seas, robbing from rich fucks and snobs and taking it all for themselves,” Dean explains launching himself, and consequently Castiel, closer to the wreckage, “sometimes they buried it on islands, and made maps that would lead back to it.”

        Castiel frowns, “Why would anyone do that?”

        “Because it’s what they did,” Dean shrugged, “I wouldn’t know – I’m not a pirate. And the ones that are around today are _totally_ different from the legends of the past. Come on, maybe there’s a treasure chest on board no one got around to burying yet.”

        He finally releases Castiel to detour over to the sunken ship. Castiel takes a moment to rub at the skin before swimming after Dean.

        The closer they get to the wreckage the more details Castiel identifies. On the seaweed-like flag a faded skull stares down at them. Barnacles pepper the shell of the vessel, a veritable ecosystem developing over the years since the ship first sunk. And at the front rests a very familiar statue-like figure.

        “I thought you said humans didn’t think mermaids were real?”

        Dean pauses and turns to where Castiel points. He chuckles, “We don’t.”

        Castiel rolls his eyes, “Then why is this here?”

        “Even if we didn’t know you were real we still had legends… stories…” Dean explains, “mermaids were supposed to have amazing powers, maybe these pirates figured having her there would help. Or give them something to stare at when it’s been too long without docking. Although…” Dean lets his eyes roam up and down Castiel’s form, “I’d have used a different model if I was in charge of the ship.”

        Castiel blushes, unsure what he means. Before he could ask, though, Dean slips into a hole and into the ship. Not comfortable with letting Dean out of his sight, Castiel ventures inside the wreckage himself.

        He freezes at the sight of the flag’s tattoo come to life.

        Dean circles the skeleton studying it. His fingers brush up against the weird draping filled with holes. Sunken holes as dark as an abyss stare back in an almost similar, morbid fascination. “This is so cool…” Dean murmurs.

        “Cool?” Castiel asks, swimming up from behind, “They’re dead.”

        “A dead _pirate_.”

        “But dead nonetheless,” Castiel continues, “In a world in which they don’t know…” Castiel reaches a hand out towards the skeleton, the image shifting for a brief second. Instead of an old stranger, he imagines Dean in his human form sitting trapped below the waters. Skin pale and clammy, eyes dim and dead. Startled, Castiel jumps back a few inches.

        “…Cas?”

        “What of their family?” Castiel asks, voice small, “Not knowing where they ended up? If they were ever safe?”

        “Cas, you’re thinking too much about this –“

        “Dying so far away from their homes,” he whispers, “far from the land that they know and lying in a grave of an unknowable ocean.” Castiel finds Dean’s worried stare and asks him. “What makes someone want to journey so far away from what they know?”

        Dean frowns, considering his question. After a few beats of uncomfortable silence, Castiel’s senses return. He repeats the descent into despair to himself, growing more embarrassed the longer it takes for Dean to respond. Castiel almost speaks up again, to tell Dean to forget what he said. By then the other merman has an answer.

        “There are lots of reasons,” Dean says, “Old Boney here could have sailed because they loved adventure, and hated rules. That pile over there,” he points to a skeleton resting on an upturned table, “maybe ran into some trouble and knew the only way out was on the sea. And the unknown was better than the terrifying known.” His focus drifts towards a third skeleton, still holding its saber. “Or they liked the killing aspect and gave into that side of them. Everyone has their reasons for doing what they do… we’re all different. But if we spend all our time trying to find reason in other people, well… you’re setting yourself up for a bad time.”

        Castiel peers past the skin and scales, squinting. “And you?”

        “What about me?”

        “Why did you go out to sea?” Castiel asks, “What reasons did you have?”

        Dean smirked, floating back over to the first skeleton. “Duty.”

        “Duty?”

        “Family,” Dean continues, “My dad can barely hold down a decent job… if it weren’t for my uncle I doubt he’d even bring home _something_. Ever since I was old enough I took any job I could to support everyone, to look after my dad and my brother. It wasn’t what I wanted to do with my life but the pay was decent… and the bonuses I could take home and feed Sammy for a week with.”

        “But your brother is grown and on his own now,” Castiel interrupts, “can’t you go and do what you want with your life now?”

        “With what education?” Dean grins cruelly, “I… It’s not so easy up there, Cas. I can’t just drop everything. The land has a bunch of rules, while the ocean it’s… it’s total freedom.”

        “Funny how we consider our homes the same,” Castiel tells him, “But if the land has rules… and the ocean has rules… is there anywhere that’s truly _free_?”

        “I’m guessing everything’s _not_ better down where it’s wetter, then?”

        “How you described your life above I… I find myself relating,” Castiel says, “There are times where I feel trapped by my circumstances, bound by a duty that I had never asked for… keeping me from pursuing what I truly want.”

        “Family expects a lot from you?”

        “My dad,” Castiel sighs, “Even though I am the youngest he expects me to be involved in the family business…”

        “Which is?”

        Castiel pauses, biting his lip. He nearly revealed to Dean some truths he’d rather not disturb lest Dean’s opinion of him change. If Castiel began speaking about his family, it would only result in more questions that could lead to Dean discovering some truths that would best remain buried.

        “Not important.”

        Dean sighs. “Cas, you can tell me –“

        “I’d rather not –“

        “I’m not a stranger to family businesses.”

        “Please, Dean, drop it.”

        “Come on, Cas, why can’t you tell me?”

        Castiel tamps down what he wants to say and instead chooses a more sobering honesty that he’d been avoiding. “Because I don’t want to ruin the time we have left together.”

        Dean’s mouth falls open, aghast at Castiel’s stern tone. But then it clicks shut with a harsh swallow. “Yeah,” he says, “I… if this is the last we’ll be seeing of each other then… let’s enjoy it.” He glances around the space, a bitter smile on his lips. “We should keep going, there was nothing here except disappointment.” The poison in those words stung Castiel, confident there was more to what he said than at first thought.

        “Right,” Castiel nods, leading him back to the path, “It shouldn’t be long now.”

        The earlier joy from Dean has faded entirely, and now they find themselves in an unfamiliar darkness. Castiel curses himself for coming out of his shell too much, latching onto Dean even though he knew what their fates were at the end of this journey.

        Besides, he thought to himself, there are things Dean doesn’t know about him. If he knew Castiel was a prince of the ocean, or that he was directly responsible for his ship sinking, then whatever way he saw Castiel would be gone forever.

        And that would break him. Because the version of Castiel that Dean knows is the only version of him that he likes, that he believes to be truly himself.

* * *

        Swimming becomes harder as the reality of where they are sinks in. The seafloor slopes upwards, off towards the line where it stops being part of the sea and is called land. He barely remembers what it’s like to smile, and for a strange reason Dean forgets as well.

        “So,” Dean says, “this is it, I guess.”

        “Yes… it is…”

        Dean stops, and so does Castiel. “Cas,” he starts, rubbing at his arm, “I… I need to thank you.”

        Castiel blushes, glancing away. “Nonsense, there’s no need to –“

        “I do, Cas,” he insists, “So… please?” He falls silent at Dean’s plea, nodding for him to continue. His words hadn’t so much robbed Castiel of his ability to speak, rather the intensity of the other’s gaze on him. It was like being stung by thousands of jellyfish and craving for more to float by. “Thank you for… for bringing me back to shore and – and well _being_ here. I thought I’d never…” He shakes his head, casting the rest of his sentence away in favor of another. “What I’m trying to say is that I… I won’t ever forget you, man. You _changed_ my life…”

        Castiel smiles as he agrees with him. “You’re an extraordinary being, Dean. I’m… I’m glad to have gotten the chance to know you as well. Even if the… the circumstances are unfortunate.” The guilt bubbles up inside him, and he quashes it there. So many other emotions are churning inside, he can’t spend time dealing with one he already knows the name of.

        “I’m nothing too special, Cas,” Dean chuckles, “There’re a thousand of me…”

        “I find that hard to believe.”

        “If you ever came out of the water I could show you,” Dean suggests, “I could show you a lot if you… if you could…” His joy seeps out of him, shoulders hunching around him.

        Seeing the light leave Dean’s eyes, Castiel reaches out to grab at his shoulder. Contact startles Dean, and his face takes up Castiel’s field of vision.

        It’s a magnificent sight that rivals many of the wonders Castiel was lucky enough to see in his life. From collections of pearls arranged in fancy patterns to giant coral trees teeming with fish, none could compare to Dean’s beauty. His face caused the confusion warring inside Castiel to spill to the surface.

        “I should be happy for you,” he admits, head skewed to the side, “you’re going home, to be with your family. Returning to your life before… yet, thinking about this… I can’t help but feel…”

        “Empty?”

        Castiel nods.

        “I… I don’t mean to sound ungrateful,” Dean says, “But I – um… I feel the same. I want to be with my family more than anything but… man, I don’t know how I can go back after all that’s happened?”

        His mood darkens, storm clouds rolling over his features. “Because of the storm? Learning about a whole world that exists adjacent to yours? Hidden under the tides?”

        “No, no… Cas, I… I need to…” He trails off, cheeks tinting an angry shade of red. “Dammit! I want to tell you…”

        “Tell me what?”

        “The feelings, I…” Dean struggles, “It’s crazy, I shouldn’t… I don’t know why –“

        “You are experiencing feelings as well?”

        “As well?”

        Castiel squeezes Dean’s shoulder. “From the moment I laid eyes on you Dean, something has been stirring… growing within me. I thought it was curiosity, but the longer I spent in your glow I realized it was something… _else_ . An _other_ . I’ve never felt anything like it and… I’m scared, but also happy and _sad_?” Castiel laughs, a pitiful, broken thing. “You may look like a merman but you’re still human, and I guess you inspired the human in me, too.”

        Dean reaches for his free hand, clutching it in his. “Cas… I don’t _want_ to say goodbye.”

        “Neither do I.”

        The next few moments happened slowly. Dean’s eyes flutter shut, face tipping closer to his. Castiel squints, unsure of what to do. His body acts for him, lips pursing in anticipation. Fins brush against each other as Castiel’s tail moves to wrap around Dean’s. There’s powerful magic brewing between the two of them, separate from the amulet Dean still wears around his neck.

        Then a horn sounds, scaring them out of their embrace. Dean turns to where the noise came from. Castiel can’t look, the notes familiar to him.

        Soldiers swim onto the scene, the sound of their shells clinking. Following them is the royal chariot. When it seems like soldiers stopped moving, Castiel turns to face them.

        He curses silently, staring into the eye of the storm – Charles’s stern, furious glare.


	4. You Can Have It All

        The soldiers might intimidate Dean, but Castiel has seen his father pull even grander stunts in his pursuit of striking fear. At least the soundtrack was decided against, Castiel unsure if he could maintain a straight face if the thundering drum beats accompanied his father’s measured swims. It wouldn’t have helped him any given the stern look slashed across Charles’s face.

        “Castiel,” he starts, “Thank you for granting us a moment of your time…”

        Dean reaches for Castiel’s hand, squeezing it. “Cas,” he whispers, “who is this?”

        He sighs, “This is my father –“

        “ _Quiet!_ ” Charles bellows, glaring between him and Dean. “Castiel, what in Poseidon’s name convinced you to journey so far away from your home.”

        “Poseidon had nothing to do with this father,” Castiel tells him, “I was doing what’s right.”

        “What’s right?” Charles asks, “Leading some unfounded crusade through our domain towards human territory? Castiel I know you have some sick fascination with these creatures but leave those fantasies behind! Come home –“

        “Not until I’ve done what I’ve promised to do,” Castiel says, meeting his father’s harsh stare with his own. “Royalty are only as honorable as their word, isn’t that what you’ve told me? Why would you want me to break it?”

        Charles groans, kneading his brow. “What’s honorable in running away, Castiel? In leaving your family in a panic because they had no idea where you went! If it weren’t for your guards we still would have been scouring the seas searching for you instead of following in your damnable chase.”

        “Guards?”

        “Hannah,” Charles glances at his friend, her posture bent and apologetic, “Saw you leaving with your… _friend_.” The words stung like jellyfish toxin, Castiel untangling his fingers from Dean’s instantly. “Reported back to me before I sent her along with your brother Gabriel alongside her.”

        His brother’s golden locks floated above his head in his own crown. He waves without any apprehension, sucking down on a stray piece of coral like his life depended upon it. Golden tail the only loose piece of muscle of the entire affair.

        “There wasn’t much to worry about,” Castiel says bitterly, arms crossed, “I’m an adult. I can handle myself.”

        “It wasn’t _you_ I was worried about.” Again his eyes bore into Dean until Castiel shifts in front of him. However, Dean stops him, swimming out from behind to get between Castiel and his father.

        “Cas is telling the truth, Mister uh – Cas’s dad –“

        “I am your king and you will address me as such,” Charles bellows, voice as thunderous as the actual lightning cracking from above. “Really, Castiel, is this the kind of blobfish you’re running around with? I know our relationship is contentious but you’re too old to still be this rebellious!”

        Castiel scoffs, “Maybe if you weren’t so pompous I wouldn’t have a _need_ to _rebel_.”

        “That is _enough!_ ” The trident glows bright, Charles swinging it around with enough force to startle the troupe around him into scattering towards a safer distance. “Whatever childish quest you have in mind ends _now_. You’re coming home!”

        “No!” Dean shouts, drawing attention back to him, “No, please, we’re almost _home_ –“

        “Boy,” Charles growls dangerously, “You’re both far from home –“

        “No, you don’t get it,” Dean tells him, “ _This_ isn’t my home –“

        “Dean, hush –“

        “I’m not from here!”

        Charles’s anger drains into a strange curiosity not unlike his own. Castiel would rather the former emotion streaked across his father’s face like squid ink than what is there now. At least Castiel knows how to navigate his father’s rage like their oceans.

        “Explain yourself,” Charles tells him, “Not from here? You are a merman are you not? That tail, while plebian, is not dissimilar from any of my other subjects.” He glares, “What sort of lies are you trying to spin for your _king_?”

        “They aren’t lies,” Dean says, “I’ve got a tail, yes – but I never had one before –“

        Castiel grabs for Dean’s hand, trying to tug him away from his father.“Dean, really, please stop –“

        Charles makes his trident flash, stunning Castiel’s attempts. “Castiel, let the boy speak!”

        Dean floats towards Charles, undeterred. “I’m trying to get home – to land. Like I was saying I’m not really one of you. I’m human –“

        The gasps of the crowd rise like a swelling tide. Dean stumbles over his words, glancing about them all in confusion before his eyes fall onto Castiel’s. He looks unsure of himself, frowning with a pleading gaze asking him what to do next. Castiel has no idea how they might remedy this, and before he could begin stringing one together, Charles’s anger boils the water around them.

        “A human!” Charles roars, speeding over towards Dean to seize his arm, “You foul, cunning – what source of trickery is this?”

        “Hey – ow, that hurts! Let go of me!”

        “Humans cannot become like us – were not blessed by the sea as we were, what could…” His stare settles on Dean’s chest, on the amulet resting there. “That damnable magician… Joshua if you were only alive in my time –“

        Charles swings his trident close to Dean, spurring Castiel into action. He swims over to them, only to be blocked by a wall of guards. Two grab him by the arms, leaving him struggling for freedom.

        Dean hovers, frozen in terror. One of the trident’s forks plays with the string of the amulet, its tip inching back and forth, fraying the wire. “What?” Dean whispers, “What’s going on? Cas –“

        “Keep my son’s name out of your hole you air breather,” Charles hisses, “I don’t know what kind of damnable magic you’ve enchanted my boy with but I will not have you carry him off to your world for whatever foul tricks you have planned.”

        “Father, no!” Castiel yells, railing against the grips of familiar faces, “Please! It’s not what you think!”

        “Humans are cruel creatures, Castiel,” Charles says, “Liars. Whatever he told you was untrue!”

        “No, no!” Dean says, head shaking, “I just wanna go home. Cas – he’s been so nice, offered to help me ever since my boat sunk and –“

        “So that’s what it is,” Charles cuts him off, “Mind games? Using pity and guilt to your advantage, playing with my son’s enormous heart?”

        Dean frowns, brows drawn up in confusion. “What – I don’t know what you mean?”

        “Father, no!” Castiel pales, obvious to him where his father’s reasoning is taking him.

        “You know it was because of us that your ship sunk,” Charles snarls, “Biding your time. Using him, leading him into a trap where you can string him up and have your way. Is that it?”

        “Cas? Cas?” Dean cranes his neck as far as it can take him, one eye able to meet Castiel’s sad gaze. “What’s he talking about? My boat…?”

        “I… I’m sorry, Dean,” Castiel says, “I should have told you… my father and I – we got into a fight the day of your sinking. Our tempers led to the storm like the one now.” The lightning raging above them strengthens his story. “It was never my intention to hide the truth from you… but I was fixing my mistake and – and we were having so much fun together, you and I. You were… you were starting to trust me. I didn’t want to lose that…” He ducks his head, unable to face Dean’s searching algae eye.

        “Cas…”

        “Enough!” Charles says, body shaking with rage, “Castiel, you will return home with me at once –“

        “Of course, father, but please! Spare Dean and let him go home –“

        “After what he knows?” Charles’s mouth fades into a grim line, “I can’t put one human over the safety of my entire people, Castiel.”

        _SNAP!_

        “No!”

        The amulet begins sinking into the deep, Dean glowing bright before his human body returns. Charles lets go, Dean’s arms now scratching at his throat while bubbles pour from his mouth.

        “No, father,” Castiel fights against the guards’ holds, “He’ll drown.”

        “Another lesson my boy,” Charles says, turning his back on them, “the ocean is no place for humans. Now come along.”

        Castiel stares after where the amulet falls, watching it become smaller and smaller. A deep-sea vent burns in his chest, muscles seizing at the tremors within. “No…”

        “What was that?”

        “No!” Castiel finally breaks from the guards as he rushes down to where the amulet is.

        “Castiel!” his father shouts after him, “Don’t –“

        He tunes him out, snatching the amulet before it can fall any deeper. Holding it in his grip, he swims faster than he ever has to reach Dean. The other man’s body stopped squirming, the enormous rush of bubbles now a small trickle. His eyes slowly lose the bright signs of life by the time Castiel makes it over to him.

        Standing in front of him, Castiel places the amulet back around Dean’s neck. He ties it deftly, without looking, staring into Dean’s ever paler face. Counting the freckles in an attempt to stay calm. His fingers don’t stop shaking until he sees light begin glowing beneath Dean’s skin.

        Moving back, Castiel sighs in relief when Dean’s merman form returns to him. He gasps for breath, hands running up and down his chest. Castiel engulfs him in a tight hug, murmuring into his hair. “I’m so glad you’re safe… Sorry, so sorry he did that, I swear…”

        “Castiel!” his father yells, swimming closer, “Castiel you take your hands off of that thing –“

        “No!” Castiel responds, facing his father, “No, I will not! I’m _tired_ of this, father.”

        “Tired?”

        “Yes,” he says, “Tired of you not listening. Of not seeing with your own eyes. There’s no spell or enchantment that makes me want to stay by Dean’s side. You know why I’ve stuck by him all this time? It’s not because of my ‘sick fascination’ with humans or because of my guilt. Dean _listened_ to me, _saw_ me… Yes, we may have argued from time to time… he made our trip _maddening_. But I was able to teach him a few things and he did the same with me.”

        “Preposterous,” Charles scoffs, “What could a human teach you that you don’t already know –“

        “That the vent above is called a sun,” Castiel says, “And the pearl is called the moon. Humans walk on legs and breathe air and have men and women and others just like we do. There are families and pets and these strange chariots called cars that people hold dear to their hart. That they believe in _freedom_ … to choose where their lives take them and with who.” Castiel smiles sadly, glancing at Dean. He reaches out for the other man, Dean taking his hand with an answering grin. “There are some bad humans, yes. But we shouldn’t judge a group of people by the sins of a few.”

        “You trust to easily, Castiel,” Charles whispers, moving ever closer, “You think you can believe the words of a surface dweller? They’ll say whatever they need to get what they want. They are selfish, look how they disrespect our home –“

        “They don’t know it’s our _home_ ,” Castiel tells him, glaring, “Centuries of isolation have turned us into tales. We _don’t_ exist to them, and because of that they have no knowledge of what consequences their actions lead to.”

        Charles meets his glare with one of his own. “And if they did?” he asks, “You think they will change their ways? Do you have enough faith in humanity or…” he casts his gaze behind Castiel, “are you blinded by the minute actions of one.”

        “I have to,” Castiel says, “Closing ourselves off from the world isn’t working. Closing ourselves off from – from _each other_ isn’t…” He sobs, grabbing for his father’s wrist with his other hand, “I meant what I said. I’m tired of fighting of – of going around in circles. We’ve played out the same fights thousands of times… I can’t ask you to be blind to what it’s doing to us any longer.”

        Charles’s face drops in surprise, frowning at Castiel’s earnestness. “What it’s… doing to us?”

        “You know,” Castiel continues, “Our contentiousness… you call it _rebellion_. I’m not asking you to trust humanity, but I do want you to trust _me_. To support me in my decisions instead of making them for me.”

        “Castiel, I…” Charles’s brows slant downwards, “I trust you, my boy. Humans, though… I don’t want you to be hurt. How can I know that by going down this road you won’t be endangering yourself?”

        Castiel attempts a smile, the chuckle coming out wet not from their surroundings. “Just me? What about your people?”

        “I am your king, Castiel, but I am also your father,” Charles says, “I love my land and my _family_. You’ve always been a sensitive starfish… it breaks my heart to see you hurt. To my knowledge, that’s all humans are able to give. What kind of father would I be if I let you continue down this path of pain?”

        “You’d be the one who’s there to pick me back up if I fall,” Castiel says, “But I won’t ever fall – I won’t ever learn for _myself_ if I don’t do this. Besides, as I’ve come to learn…” He darts his gaze quickly to Dean behind him, “Sometimes the greatest risks have the best of rewards.”

        Charles follows Castiel’s eyes, frowning. “Your mind is made, isn’t it?”

        “It is.”

        He sighs, crushing Castiel in a hug. “You’ve always been the most like me Castiel,” he admits, “Stubborn, a servant to your heart… but with a good head on your shoulders. If this is what you want to do…”

        “We’re almost done,” Castiel says, “Promise.”

        “Then… it would be unkingly to break your word so close to its completion.” Charles moves back, posture more calm. The water above them calms, and for quite some time the accompanying storm was quiet. “When you return home, we can discuss more about your… interests.”

        Castiel beams. “I would like that.”

        Charles clears his throat, turning to Dean. “You, human –“

        Dean stiffens, frowning. “Yes – yes, sir.”

        “For your sake you better be telling my son the truth,” Charles says, “For if this is the last I ever see my boy… humans won’t think of my people as stories anymore. We’ll be something for you to _fear_.”

        Dean gulps. “Of course.”

        Charles whistles for his troops to gather, returning to his chariot. With one final parting look, he and everyone leaves until Dean and Castiel are alone once more.

        They sag into each other, hands still clasped between them. “That was the worst ‘meet the parent’ I’ve ever been through,” Dean sighs. He squeezes Castiel’s hand. “So… prince, huh?”

        Castiel colors. “Again, I apologize for the deceptions,” he says, “Is there any way I can get you to forgive me?”

        “Well you did save my life…”

        “Dean.”

        “Okay,” he says, “Only if you tell me one thing.”

        “What is it?”

        “There’s nothing else you’re keeping from me?”

        Castiel stills, biting his lip. The confession from earlier weighs heavily on his mind, biting into him with jagged teeth like a broken piece of shell. There is still more to be said, to be done, that was stolen from them by his father's arrival. However after all of Castiel's secrets were laid bare, the shifting mood left Castiel feeling trapped in a riptide. With only a few strokes away from the shoreline, Castiel decides to let the pain stay. With what's left of his strength, he tightens the grip on his heart and prays nothing else happens that could break his steely façade.

        He sighs, forcing a smile. “Nothing,” he lies, “I have nothing left to say.”

        Dean eyes him, staring as if he searches for something to scrutinize. Castiel hopes he doesn’t find the cracks in his mask. Unable to find anything, Dean shrugs and casts his gaze elsewhere. “Well, um,” he says, “Land?”

        “Land.”

        They swim together, hand in hand.

* * *

        Dean toys with his amulet. He stares at the shoreline, floating alongside Castiel who watches him. They’ve been like this for a long while, unmoved by the final strokes over to the finish line.

        “So,” Castiel says, voice rough and thick, “this is your home?”

        “Not – not really,” Dean tells him, “I mean, this is _definitely_ where I’m supposed to be.” He points out towards a length a good distance away. “This is where we set off, the ship that is. My home though… it’s a little further in.”

        Castiel hums a thoughtful note, dropping back into silence. Their hands broke apart earlier, yet his fingers twitch to return. Instead he clamps down that desire and pinches his tail like a crab.

        “Y’know,” Dean chuckles, “After all this swimming… I’m not sure I’ll remember how to walk again.”

        “It shouldn’t be hard.”

        “Says the guy who’s never walked a day in his life.”

        Their gazes meet, neither wanting to duck away. Dean turns away from the shore to fully face Castiel, and he does the same. His grip on the amulet tightens, and he tugs it off. Castiel doesn’t blink as Dean undergoes the transformation one final time, his human body appearing. He holds it out to Castiel, waiting.

        Castiel frowns, “What are you –“

        Dean shakes it, saying something. Like he wants Castiel to take the amulet from him.

        His eyes widen. “What? Why would you…”

        Dean smiles, tapping at his temple with his free hand. Communicating as best he could his final wish. Castiel understands easily.

        “A token to remember you by?” he chuckles, “Like I could ever forget you.”

        His decision is moored.

        Castiel hesitates a beat longer than he should. Dean rolls his eyes and moves to take his hand and drops it in, curling Castiel’s fingers around it protectively. He tries pulling away, but with his other hand Castiel snatches his wrist and holds him there.

        “Cas-?”

        He cuts him off with a kiss, startling him. Castiel couldn’t hold himself at bay any longer; Dean’s touch electrifying like an eels’. Knowing that this would be the last they will ever see of each other was one thing. In the moment, his emotions stirred and boiled until they explode, and Castiel needed to tell Dean all he feels. Words wouldn’t do it justice, without the amulet. They break, Castiel gasping for no reason other than from the exhaustion of this moment. His body years to cling to Dean like an octopus. He lets go, however, to let him be free.

        Dean follows before coming back to himself. He touches his lips, smiling, wiping at his eyes. Then he turns and begins swimming back to shore, legs kicking all the way. Castiel waits for him to reach the shore, the amulet burning his hand.

        Climbing onto the beach, Dean stands at his full height. He looks as beautiful as he was on the island and every moment in between during their journey. The moonlight shines across the water, highlighting his features so Castiel can etch them into his memory.

        Sighing, Castiel begins sinking into the ocean. His vision blurs, and he pauses to regain control. The amulet still stings, so he grabs it by the cord and holds it up. “Dean,” Castiel sighs, “I’ve never felt like I belonged… until I met you.”

        Swimming while holding the amulet would be difficult, so Castiel decides to wear it himself.

        Blinding light. Searing pain. Castiel screams silently as his body breaks and reknits itself in a new form. His mind whites out, the last thought asking if this was what Dean felt every time he put the amulet on. When the glow dims, Castiel becomes aware of how dark the waters are, and that he can’t breathe.

        Castiel claws his way to the surface, splashing around and yelling. His tail split in two, and he has no idea what to do with them. Someone screams, and in the back of his awareness he realizes it’s him. But then another voice joins the fray, telling him to “Stay calm!” “Breathe!” and “Hold on, Cas, hold on!”

        He and Dean wash onto shore, both weak and hyperventilating. Castiel scrabbles for purchase on anything solid, finding none of that on the soft, sandy beach. Pulling himself up, Castiel stares down at where his tail should be only to see two legs and a strange length not unlike Dean’s.

        “Cas!”

        Dean scrambles to his side, grabbing his face. “Cas,” Dean says, “Are you okay? Cas? Cas –“

        Castiel jumps forward and tackles Dean to the ground in another kiss, tangling his hands in Dean’s hair. He drags himself away, grinning overhead. “Dean.”

        His eyes light up. “Cas,” he says, “I can… I can understand you. But –“

        “The amulet,” Castiel whispers, “works both ways apparently.”

        Dean giggles. “Just like the Little Mermaid…” He shifts underneath him, banging against something. “Woah,” he says, “excited there, Cas?”

        “Hmmm?”

        “Never mind, let’s get up.” Dean pushes Castiel off of him, standing once more. He offers his hand to Castiel, helping him up. Wobbling on his new legs, Castiel manages to stay upright for a beat before falling into Dean’s waiting arms.

        “This is… more difficult than I imagined.”

        “Told you.” Dean hefts him up, throwing Castiel’s arm over his shoulders. “Now come on, we should get you some clothes before someone finds us.”

        “Dean?”

        “Yeah?”

        “What are clothes?”

        Chuckling, Dean drops a kiss onto Castiel’s head. “I’ll tell you later. I’ll tell you… everything later.”

        “Yes, later,” Castiel hums, “I like later.”

_Epilogue_

        Dean and Castiel pause at the entrance of a small, one-story house. Castiel marvels at the sight, like he did all the other houses before when they walked down the hard path. It was a strange sensation, the stone on his feet – not very comfortable. Thankfully Dean stole him a pair of coverings he called ‘flip flops’, along with a ‘shirt’ and ‘shorts’. He would grow use to the feeling in time, but he did enjoy the sound they made when he stepped.

        “This is it,” Dean says, offering a grand flourish, “My home. It’s no _palace_ , but…”

        Castiel smiles at him, squeezing his hand. “I think it’s _lovely_.”

        Chuckling, Dean scratches at his head. “You won’t feel the same after getting a look inside,” he tells him, “So long since I’ve been here… food probably spoiled.”

        “Even if it’s a mess it’ll still be the best human house I’ll have seen,” Castiel says.

        “You’ve never seen a human’s house before.”

        “Exactly!”

        “You’re such a dork…”

        Castiel frowns, tipping his head to the side. “What’s that?”

        Dean rolls his eyes. “Someone who’s super loveable, even when they’re being an idiot.”

        Saying nothing further, the two journeys toward the house. Dean grabs a stone and turns it over, revealing a hidden piece of gold underneath. “Key,” he says, tearing it from the stone like it was nothing; “so we can get in.”

        Castiel bounces while Dean drags the process out. He sticks the key into a ‘lock’, twisting it before resting his hand on the ‘knob’. “Welcome,” he says, “to Casa de Winchester.”

        A light flickers to life, and Castiel glances around. He frowns, turning to Dean. “This isn’t so bad Dean,” he starts, “My brothers are much messier than this.”

        “What?” he mumbles, moving past the entrance and further into the room, “This doesn’t make any sense…” Glancing at a small table, Dean picks up a strange book. He runs his fingers across the shiny marks over the cover. “But… if this is here, then –“

        “Put down the laptop and keep your hands where I can see them!”

        Castiel hisses, throwing his arms out wide and crouching at the intruder. A taller man with long hair stands under a darkened archway; grip tight on a smooth club. His eyes dart from Castiel to Dean, startling when it reaches the latter. “D…Dean?”

        “…Sam?”

        The club drops. Sam runs towards Dean, trapping him in his arms. Castiel nearly jumps to his defense, stopping only when he notices the water pooling at Dean’s eyes. Dean sniffs, pulling back. “Sammy, I –“

        “We thought you were a goner,” Sam says, “The storm came from out of nowhere… the ship – how did… they said no one could have survived?”

        Dean glances behind him to Castiel, smiling. “I wouldn’t have if I didn’t have any help.”

        Sam finally takes notice of Castiel, turning to him. Castiel offers a small smile and a shrug. He’s swept up in a hug by the other man, crushed tight in his hold. “Thank you,” Sam says, “thank you for saving my brother.”

        “You’re – you’re brother,” Castiel squeaks, “You’re ‘little Sammy’?”

        Sam lets go, frowning. Dean laughs, clapping him on the shoulder. “I said he grew like seaweed, Cas. He’s little only in name…”

        “Even I don’t tower over my eldest brother,” Castiel murmurs, staring between the two Winchesters.

        Sam gives Dean his attention once more. “Seriously though, we were all so worried. Bobby’s been out on his own boat searching… and dad hasn’t been to the bar since we first heard the news.”

        “Well that’s a first.”

        “Dean just… what happened?”

        He sighs, reaching out for Castiel. Their hands intertwine, Dean leading them to a nearby lump. “Sit,” he tells him, “it’s called a couch. They’re comfy.” Castiel does, sinking into the cushiony fabric. Dean joins him, smiling up at Sam. “You might want to do the same,” he says, “it’s a pretty long story and… well, there are a few things you might not believe.”

        “I don’t know,” Sam says, sitting across from them, “I’m ready to believe in any miracle –“

        “Not miracles, Sammy,” Dean interrupts, “ _Mermen_.”


End file.
